Thread: Intake choices, new ideas...

Did a lot of searching about various custom air intake setups for the GXPs, right now I'm mulling over a few different options in order of $$ investment and level of effort.

1. Increase the air inlet size + K&N panel filter.
2. Typical DIY heat shielded short ram-air cone intake type system
3. Both 1 & 2... minus the panel filter obviously
4. FWI
5. Twin intake possibility?

My question to you smart guys out there, would it be possible (and worthwhile) to incorporate a twin intake setup, i.e. two cone filters customized to feed either the current intake setup combined with maybe option 1 above or possibly a larger 4" custom setup as mentioned in another post? Has anyone tried this? Is there a point of dimishing returns? No matter which route I go the car will be getting a new tune to accomodate the larger air flow.

Does anyone have hard data that would support any one of these over the other? I know there isn't a lot of room to play in these cars but I'm sure if you get crafty the twin intake could work.

Am I insane or what?

I think you're spending too much time worrying about an intake.

But I'm no engineer.

I do like the part where you mention a tune.

That with any of the options will be nice.

You are probably right, being that I'm an excel junky I get wrapped around numbers too much sometimes. What I think would be cool is if we had a data forum for people to post real dyno results before and after a mod. I know not everyone does this or has the money for it but over time it could probably help people make good choices based on reasonably good data.

Hm. Maybe get a nicer filter than K&N. I'd go with cheap short ram. If there's benefits to fenderwell, you might not notice. I happen to prefer the look of a 9"x4" filter, though, over airboxes. As for twin intake... probably too much work for no return.

There has been discussion on this forum for a while about whether or not the stock setup was really that restrictive. K&N provided me some pretty hard data to back this up. The bottom line here is that the engine max CFM at 6000 RPM is 451 while the K&N panel filter can provide 592.4 CFM, the airbox restricts flow to 240 CFM. So the running while breathing through a straw analogy applies. Just thought I would pass this on.

"Thank you for your interest in K&N products. A stock engine usually has a volumetric efficiency in the high 70% to mid 80% range which would put the CFM of your motor at 451 CFM at 6000 RPM. That is the maximum amount of air that your engine car draw in so, even if your use a filter that can flow 800 CFM, your engine will still max out at 451 CFM and there won’t be any performance gain.



The CFM of a filter is based on its surface area and our 4 layer cotton filters flow around 6 CFM per square inch. Horsepower gains from the intake system are primarily from designing a more efficient and smoother intake tract. As you can see from our air flow test data, our panel filter can flow 592.4 CFM on its own, but in the stock, restrictive airbox, it can only flow 240 CFM.

http://www.knfilters.com/dynocharts/33-2334.pdf



By eliminating the airbox and using a smoother intake tube, the efficiency increases and the CFM capability of the system is greater than the requirements of the engine.



The only benefit of using a filter that flows more CFM than your motor needs is that it extends the service life because there is more surface area to draw air through before the filter becomes clogged. With that being said, a twin intake will provide no performance gain and will only be for aesthetic purposes. "

Then gut the box and smooth tube?

or rip the box out and try and sell it...much simpler

honestly...i think someone might...a non-car person who wants to keep their car stock for resale purposes...

Originally Posted by matt5112

Then gut the box and smooth tube?

Thinking about something along those lines.

^^ well...if it goes horribly wrong, you know where you can get a replacement box (right here)

Originally Posted by GeeXPee

Forced induction systems don't allow for greater flow rates in terms of CFM than what is set by the displacement of the engine. What t/c, s/c systems change is the amount of mass in lbs/min of the air coming into the engine, greater mass = more power so no it doesn't really go out the window.

I was providing the info for the 5.3 folks many of which haven't opted for the 5k cartuning turbo thats out there so I thought it may be of value to someone.

I don't follow.

The VE goes up, so does the CFM.

You could back up at look at it this way, more power requires more air to be pumped through the motor in the same period of time.

Originally Posted by GeeXPee

Thinking about something along those lines.

Let us know how it goes.

Originally Posted by jcmonteman

or rip the box out and try and sell it...much simpler

Originally Posted by jcmonteman

honestly...i think someone might...a non-car person who wants to keep their car stock for resale purposes...

Originally Posted by jcmonteman

^^ well...if it goes horribly wrong, you know where you can get a replacement box (right here)

:C

All force induction system do is put more air in the same volume of space...CFM will go up (max out based on size) but the engine still can't exceed it's max CFM determined by the cu in size of the engine...that doesn't change. Volumetric efficiency doesn't go up just because the CFM is higher it's also because of the larger mass of air compacted into that same volume.

I'll take pics when I do my intake and let ppl know how it goes.

Thanks for the tips.

Isnt CFM based on displacement and VE?